This circuit with TTL compatible output was found in a 1968 US documentation. The circuit is powered by 5 V and the frequency can be changed by changing the crystal.
This 2002 circuit uses many more electrical components than electronics. The keys are common, and...
This circuit is from the National Semiconductor CMOS manual of 1977. What this circuit does is to...
This circuit warns you if you forget to turn off the car light and leave it. The circuit is from a...